Aluminium die cast components are used increasingly in automotive engineering. Here, there are requirements for die cast components which are produced more and more precisely and are also large in size. The cast components which are produced using die casting are subjected to different treatment processes in the prior art, one method step being truing the cast components to the specified dimensions. Here, the cast components are trued in stamping dies which exist in single-piece or segmented form.
German Patent Publication DE 102004043401A1 discloses a truing method which operates using segmented stamping dies. A multiplicity of components are still trued by hand.
Truing of the cast components is a complex work step which there is a desire to avoid as far as possible in industrial manufacturing. The aim is to obtain highly precise cast components from a die casting process, which cast components correspond to the specifications without further outlay with or without a further thermal treatment step.
A conventional method is illustrated in FIG. 1a. In the first step (casting 1), the casting component is produced using die casting or else in another casting process. In die casting, the rams of the moulds are first of all positioned by way of hydraulic cylinders and the die casting mould is closed by the casting machine. The filling chamber of the die casting system is loaded by means of compressed air with the required metal quantity for each casting by way of pressure loading of the liquid metal surface of the dosing furnace. The liquid metal is then pressed in during the “casting.” Here, the piston rod of the casting cylinder of the casting machine exerts pressure on what is known as the casting tablet. The filling chamber for the liquid metal is connected via the casting channels to the mould cavities and is thus kept under pressure by way of the liquid alloy. The liquid metal thus passes under defined pressure and temperature conditions into the mould cavity which is formed by way of slides and cores. Here, the slug for the actual die casting article is produced during cooling. The casting subsequently cools while the mould is closed. The mould is opened and a robot removes the respective casting.
In step 2 (cooling of the cast component in the water spray), the cast component 10 is subjected to cooling. Here, the cast component 10 is sprayed with water or another liquid with a high thermal capacity in a defined time period. As an alternative to this, the cast component can also be dipped. As a result, the cast component is cooled rapidly from the removal temperature from the casting mould to a temperature at which the cast component can be fed to further method steps. To this end, a robot removes the cast component from the casting mould, by said robot gripping the casting tablet of the cast component and removing the cast component together with the casting tablet and moulded casting flow runners from the mould. The casting tablet with all the components moulded thereon, including the cast component itself, is introduced into a station for a water spray. The cast component is locked in the station via the casting tablet and is sprayed with water there.
After the cooling time, the robot removes the casting tablet and cast component from the station again and deposits them in the station 3 for stamping the cast component. The casting tablet and casting flow runners are cut off there in a cutting tool. As an alternative, the methods of sawing, laser and plasma cutting can also be used.
In step 4, the thermal treatment of the cast component takes place. Here, the thermal treatment is not a step which definitely has to take place, but is rather present optionally. The thermal treatment can be thermal treatment of T5, that is to say artificial ageing, or solution annealing. In solution annealing, a customary thermal treatment process for aluminium die cast parts, a temperature is set between 460° C. and 500° C.
Overall, the cast component experiences a distortion after its production in the die casting mould and a possible thermal treatment, with the result that the cast component no longer corresponds to the specifications. The truing of the cast component to the desired final dimensions therefore takes place in step 5, the cast component being cooled completely in said method step.
The machining 6 of the cast component would be realized in a last step.